1. Field of the Invention
The present invention relates to the field of image display, and in particular to a backlight dimming circuit, a dimming method of the same and a liquid crystal display thereof.
2. The Related Arts
Nowadays, the main theme of the industry is green energy saving and environmental protection, especially large-size liquid crystal display needs to save energy. Take 48 inch as example, total power is 120W, wherein the backlight power is approximately 60W, which accounts for 50% of total power. Therefore, in the green energy conservation of the products, the energy conservation of the backlight will play an important role. There are multiple techniques to adjust the brightness of the backlight to save energy through a variety of ways.
The first is manual dimming, that is, the user manually adjusts through an operation menu. This method is not smart, and manual adjustment leads to complicated operation. Furthermore, manual adjustment is not real-time because the brightness of the screen changes constantly.
The second is the ambient light sense dimming, that is, sense the ambient light levels by the ambient light sensor, such as photodiode or transistor, convert the brightness perceived by the ambient light sensor into current or voltage, and automatically adjust the brightness of the display backlight by a processor based on a preset threshold. When the brightness of the ambient light is high, the backlight of LCD is automatically adjusted to high-brightness; when the external environment is darker, the backlight of LCD is automatically adjusted to low-brightness to reduce the power consumption of the backlight. However, this method needs the perception of the light sensor on the brightness of the ambient light, which is not real-time and slow response. It also requires MCU hardware to support, so the costs are higher.
The third is local dimming, that is, divide the entire screen into several matrix regions, MCU proceeds with analysis and calculation according to the screen brightness of each region, and then independently control the brightness of the backlight of each region. This method also requires MCU hardware to support, the use of LED driver becomes more as more regions, and the algorithm and the timing control become more complex, which greatly increase the entire costs.
In summary, provide a backlight dimming method with low-cost and real-time is a goal of the industry's ongoing efforts.